PWM modulation assembly of H-bridge drive circuit

Abstract

The invention provides a PWM modulation assembly of an H-bridge drive circuit. Four switch tubes of the H-bridge drive circuit are NMOS tubes. Gates of the switch tubes are respectively connected withthe drive circuit; the input end of the drive circuit is connected with the signal output end of an H-bridge drive signal generation circuit; the H-bridge drive signal generation circuit continuouslyoutputs a conduction signal to the drive circuit corresponding to an upper tube on one side, continuously outputs a cut-off signal to the drive circuit corresponding to a lower tube on the other side, and alternately outputs cut-off and conduction signals to the drive circuits corresponding to an upper tube and a lower tube on the other side. According to the modulation assembly, the upper tube on the first side is always in a conduction state, and large parasitic capacitance exists between the grid electrode of the upper tube on the first side and the power supply voltage, so that the storage capacitance of a boost circuit is greatly reduced; and the upper tube on the first side is conducted, and the lower tube on the first side is cut off, so that the output end of the H-bridge drive circuit cannot generate negative voltage, and the circuit works more reliably than before.

Description

technical field [0001] The invention relates to an H bridge drive circuit, in particular to a PWM modulation component of the H bridge drive circuit. Background technique [0002] Integrated H-bridge driver chips are widely used in DC brushless motors. In the traditional H-bridge drive circuit designed with integrated circuit technology, the upper tube of the H-bridge generally uses a PMOS tube, and the lower tube of the H-bridge generally uses an NMOS tube. When the withstand voltage and area are equal, the on-resistance of the PMOS transistor is much larger than that of the NMOS transistor. In applications where the driving current is large and the on-resistance is required to be small, using a PMOS tube as the upper tube of the H-bridge requires a very large area to achieve a small on-resistance, which makes the chip cost high and packaging difficult. This leads to the fact that in the case of high-current applications, the general H-bridge is implemented with discrete ...

AI Technical Summary

Problems solved by technology

However, since it takes time to turn on the device, in order to prevent the through current, after the upper left transistor M1 is turned off, the left lower transistor M3 is turned on. During this switching period, the inductor current will briefly return to the load through the body diodes of the right lower transistor M4 and the left lower transistor M3. Inductor L1, resulting in a negative voltage at the first output DO

[0005] In order to solve the above three shortcomings of the NMOS tube used on the H-bridge and the negative pressure problem generated by the H-bridge during PWM speed regulation, it is necessary to design a new type of PWM modulation component for the H-bridge drive circuit

Images